Due to developments of magnetic resonance and magnetic coupling wireless energy transmission and research breakthrough of ultra-speed charging battery materials in recent years, much more attention has been put on researches regarding the distribution of moving charging nodes in wireless sensor network (also known as charging trolley) to achieve sensor energy supplement in the network.
Wireless sensor network is typically applied in surveillance sector, hundreds or thousands of sensors distributed in the network are used to collect data and transfer the data to a base station by using its own communication model directly or through jumpers. The base station collects all the information and sends the information to surveillance personnel to achieve the purpose of monitoring. Process of information transmission includes data treatment, integration and node-to-node communication, which are all the main causes of sensor energy consumption.
In order to guarantee the durability of the wireless sensor network (WSNs) during surveillance cycles without consuming all the energy in the network, a practical and effective method must be established to recharge the sensor nodes in the network and to achieve best charging trolleys dispatch which enables the total consumption of the charging trolleys to be the minimum in every charging task.
As put forward by Y. Shi in document, “On renewable sensor network works with wireless energy transfer. Proc. of INFOCOM, IEEE in 2011”, the use of distributing charging trolleys in WSNs, which can visit every sensor in the network periodically, to achieve sensor energy supplement is limited by fixed time intervals.
Researches related to charging methods for wireless sensor network distributed with multiple charging trolleys mainly involve two aspects of problem: one, choosing a shortest path to achieve minimum consumption; and two, scheduling of the charging trolley.